"January is named after Janus the god of gates, doors and doorways. How about a theme of books featuring gates, doors and doorways for January? ... and, I suppose (heaving a big sigh), even portals (for our sci-fi loving friends)."

Don't worry if you don't immediately have many ideas. I was stumped too. I could only think of literal physical doorways, like the gates to Willy Wonka's kingdom in Charlie And The Chocolate Factory and the gates of Moria that Gandalf spends so long opening in The Lord Of The Rings.

By this stage, I was convinced it was an excellent theme. It also occurred to me that since Janus is also the god of beginnings and transitions it might be worth considering books with grand openings and transitions. The two that sprang to my mind were the proud blank verse ("Of man's first disobedience, and the fruit/of that forbidden tree...") before the fall in Paradise Lost, and the curtain-raiser for Richard III: "Now is the winter of our discontent made glorious summer by this sun of York." But any other ideas along those lines would be gladly received.

Finally, DylanWolf came back with another fine series of suggestions:

"I've thought of a few (A Gate At the Stairs by Lorrie Moore for example), but if it is less than fertile ground perhaps we could throw in Janus' two-facedness as well and have doppelgangers (Dostoyevsky's The Double and so on) and split (or shattered) personalities Dr Jeckyll and Mr Hyde type stories."

Dylanwolf also added, "Although thinking of examples now sort of spoils the fun for January" - and that sounds like a good cue for me to stop typing and hand over to you.